Comparator having magnetically coupled indicator



April 8, 1953 1.. c. KRAUSE 2,636,278

COMPARATOR HAVING MAGNETICALLY COUPLED INDICATOR Filed March 30, 1948 5 A 25 :4 4 lnven tov:

Leo C. Kvause, b MC His AttOTfiEBH Patented Apr. 28, 1953 COMPARATOR HAVING MAGNETICALLY I COUPLED INDICATOR Leo C. Krause, Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Application March 30, 1948, Serial No. 17,830

6 Claims.

My invention relates in general .to gauging apparatus for measuring the diameter and circular trueness of cylindrical or tubular articles, particularly those of thin-walled character such as the shells of electric lamp bases, for instance.

To obtain accurate or true gauge readings of the diameter and circular trueness or out-froundness of thin-walled cylindrical articles, such as the metal shells of electric lamp bases, it is necessary that the gauge exert as little pressure as possible against the walls of the article in order to assure the absolute minimum possible compression or out-of-round distortion of the article. Where the gauge embraces a conventional type of dial indicator or dial micrometer, such as is commercially available at present, even the slight additional pressure exerted on the test specimen by the conventional helical pull-back spring of the dial indicator acting on the actuating spindle or gauge contact thereof, is apt to distort thin-walled articles slightly out-of-round and thus give untrue readings of-the diameter and circular trueness of the article.

It is an object of my invention, therefore, to provide an improved out-of-round gauge of 'the dial indicator type which will ive true readings of the diameter and circular trueness of cylindri-' cal articles and particularly tubular articles of thin-walled character which are easily distorted into out-of-round shape.

Another object of my invention is to provide an out-of'round gauge of the above character which will exert a, minimum compressive force against the walls of the test specimen and which will provide true and accurate readings of the circular 'trueness of the specimen.

Further objects and advantages of my inven-'- 'tion will appear from the following description of a species thereof and from the accompanying drawings in which:

Fig. 1 is a perspective view, partly broken away, of a gauge apparatus comprising my invention; Fig. 2 is a longitudinal vertical section of the apparatus, and

Fig. 3 is a transverse section of Fig. 2.

Referring to the drawings','the gauging apparatus according to the invention comprises a metal housing or frame I consisting of an elongated bed plate 2 joining a pair of side plates 3, 4 intermediate theirupper and lower edges. At the forward end of the housing I the bed plate 2 is formed with a bearing block portion 5 to the upper side of which is fastened an anvil plate 6 provided with a rearwardly facing straight edge on the line ,3-3

surface 1 extending transversely of the housing and forming the stationary or anvil contact of the gauge.

Slidably mounted on the housin I above the bed plate 2 for reciprocating movement longitudinally of the housing is a plate-shaped follower slide or rider 3 of steel or other suitable magnetic material, and provided with a forwardly facing straight edge surface 9 which extends parallel to and faces the stationary contact I and forms the movable contact of the gauge. As shown in Fig. 2, the facing edge surfaces Land 9 of the anvil plate 6 and slide 8 are beveled or tapered to diverge upwardly away from each other and provide straight knife edges I0 and I I adapted to engage the test specimen I2. To assure maximum sensitivity and fidelity for the gauge, an anti-friction slide mounting is provided for the follower slide comprising a plurality (four in the particular case shown) of small support roller bearings I3 which are carried on studs I l projecting from the sides of the slide 8 and which ride in elongated raceways or grooves I5 formed in the inner sides of the housing side walls 3, 4 and extending longitudinally thereof. An upstanding finger grip pin I6 is provided on the slide 8 for enabling convenient manual slidin movement thereof.

The test specimen I2 to be gauged (in the particular case illustrated the shell portion I! of an electric lamp base) is inserted and rotated between the stationary and movable straight edge 1 contacts I0 and II of the gauge, with its rim end I8 resting on the upper surface I9 of the bed plate 2, as shown in Fig. 2. To enable gauging of the cylindrical test specimen I2 at various distances inwardly from its rim end I 8, the anvil plate 6 and slide 8 are spaced upwardly from the upper or rest surface IQ of the bed plate 2, and one or more shim plates 20, H are inserted between the bed plate and the slide, the said shim plates being reversible and slidable on the bed plate forwardly into and rearwardly out of specimen-supporting position. In the particular case illustrated, the lower shim plate 20 is made of one-eighth inch thickness and the upper plate 2 I is made of one-sixteenth inch thickness, while the contact edges Ill and I I of the anvil plate and the slide are spaced one-sixteenth inch above the uppermost shim plate 2|, thus permitting gauge measurements of the test specimen at distances of one-quarter inch, three-sixteenth inch, one-eighth inch and one-sixteenth inch inwardly from its rim end I8. To permit the gauging of the inside diameter of tubular articles, the anvil 3 plate 6 and the slide 8 are provided with small upstanding pins 22, 22 adjacent their facing edge surfaces '1! and 9, over which pins the open end of the tubular article is positioned and rotated while the pins are held against the inside wall of the article.

The follower slideor rider '8 is resiliently held against the test specimen 12 by oneor the other of a pair of compression coil springs 23 and 24, depending on whether the outside or inside diam-' eter of the specimen is to be gauged 'lhe springs 23, 24 are mounted in end-to-end relation-.on-"an' adjusting rod 25 which extends longitudinally of the gauge beneath the bed plat'e 2' and is slidably mounted on the gauge housingl forsliding move ment longitudinally thereof. The pressure of the springs 23, 24 is applied to theiollowen slide 8 through an inverted U-shaped bracket 25 fastened to the undersidelof the slide through a spacer block 27 which extends through and moves within an elongated slot 28 iii-thebed plate 2. The depending arms 29; 290i the bracket-L26 overlie the outer or distal ends of the springS' ZBJ 24 so as to be engageable' therewitn andtheyare provided with apertures 30; 30 through which the ad'- justing rod 25 extends-withaloose fit so=asnot to interfere in any'wa'y'with the free'aind' easy sliding movement of the follower slide Borl the ea'uge housing I. An adjustableT shapedtspring stop 31, interposed between and: engageable withthe facing or adjacent ends of the spr-ings' 23,=" 2t to separate the latter, isslidably mountedo'n the adjusting rod Z'Efor'adjuStment into a set ppsition wherein it compresses 'one or the 'otherof the springs, depending onlwhethertheifollower slide 8 is to be urged forwardly'to gauge' the outside diameter of the test specimeir or "rearwardly" to gauge the inside diameterof the-specimen. I To set or fix the spring stop tl-in adjusted position, it is provided with a rider orsho'e portion32 -hav ing a tongue 33'which rides in a-longitudinally extending slot 34* in the housing side wan 3 and which is formed with "an "outwardly proje'cting threaded stud 35 on which is screwed a' positionlocking wingnut 36, with a' Washer 31' interposed between the nut-36 and the outer side of the housing side wall 3; Tightening of the locking-nut} 35 on the stud 35 clamps the shoe portion 32 or the spring stop 3 legainst the inner-side of thehousing side wall 3,thereby lock-ing'the spring stop 3l in its adjusted position on the an 25.

The movementof the -follower slidefi inaccordance with the variations'iri the diameter'o'f the test specimen 12, as the latter is rotated 'b'etWeen the gauge contacts 10 and H; is'recorde'd'on a. dial-type indicator or inicrometef 'tfl which is slidably mounted on the bed" plate z-of "the gauge housing I at the-rearend'thereoff'The dial indicator 38 is of a standardcommercialtype'gsuch as manufactured by the Federal Products Corpo ration of Providence, Rhode Island;-for instance, and comprises a housing 39,-anactuatingspindle 40 projecting from and reciprocable-inwardly and outwardly of'th'e housing-'39, a'dial ll' p 'd with suitable scale markingson the face" thereof, a pointer needle 42 pivotably mounted Ol'l' t'hB housingss to swing around the -faceofthe dial 3 1 and means within the housingca comprising a rack is-on the" spindle Miami awe-operating train of intermeshing gears 44, 451and '46 f r translating the reciprocating. movement of the spindle 40 into rotationait movement of thefindicator needle shaft MLtothe'reb sWing .theindicator needle '42 around" the dial: 4i suchu'commercial type? dial; indicators;v areialsoausually pro vided with a pull-back tension coil spring (not shown) which normally maintains the indicator spindle 40 in its outermost position. In accordance with the invention, however, the dial indicator 38 actually employed is not provided with any such spindle pull-back spring, as a result of iwliich the spi'ndle 40 is free to float between its inner and outerlimiting"positions. Instead of being provided with such a pull-back spring, the dial indicator 38 according to the invention is provided withasuitable permanent magnet 68 on :the outer-end of the spindle 40 which mag et, by

reason of its magnetic force of attraction for the I 'steel'follower slide {will continuously remain in contact "With"and accurately follow the sliding movement of the said'slide 8. By the use of the l m'agnet' 48 instead of the conventional pull-back spring, the pressure exerted on the test specimen Why the follower slide 8 is therefore kept to a minimum, whereby the possibility of out-of-round distortion of the specimen is-niinimized Also, a more unirorm*gauge?ccntacrpressure is exerted on the test specimeniance the pressure of the spring-s23;zmvwhicn'arexmuch'longer than such pull b'ack"springs and 'are adjustable for gau contact pressuregdoes not vary-as much as'that of such pull' b'a'clrisprings-throughout the relatively small range. of? movement which the follower slid'e S undergoes when gaugingthe circular trueness of cylindrical articles.

' As showngthe' dialindicator-GB is mounted on theped plate?zrwithsitsplunger or'a'ctuating' spindie 45' projecting forwardly toward the follower slide 8' so" as 1 to) be engageable with the rear ed ie-thereon Infadditiom the"dial indicator 38 is adjustable'longitudiifally otthegaugehousing i to bringitheimagnet'Mionthe end of spindle 48 into engagementiwith'the'rearedge 490i the followerslide'andto set the dial indicator in proper gauging position. For I such purpose, the bed plate 2'?of the gauge housing at is slotted inwardly from itsrearmosir end to "provide a longitudinally extending guideway 50, the ways 5| of which have a'slidingtfit invparallel grooves 52 formed in the back: 53' 0f thedial indicatorhousing 39. The adjusting'rod 25 issecuredat'its rear end to a block 54*liastenedon"the dialindicator back 53, while its forward'end is supported in the-bearing block Stand is: provided-with a scr'ew-threaded portion 55 on which is screwed-an adjusting thumb nut or wheelriis." :Th'e said adjustingnut 56 is freely rotatable within; but locked against movement longitudinally of 'the'gauge' housing I by engagementwith the walls of atransverse slot 5'! formed mithe bearing block 5 ct the'bed plate 2. Rotation of the adjusting nut SEsIideS-the adjusting rodz25 which, initurng: moves the dial indicator'ilt forwardrorbackgdepending upon the direction of rotation of the nut" 56.

In the use of the gauge according to the'i'nvention for: measuring the' diameter and circular trueness'ror'out of roundness of a cylindrical article 'orztes-t specimen l2, a cylindrical comparator or master plug of a known diameter, which either approximates or corresponds exactlytcthe diameter which the test specimen I2 is supposed to possess,- is:rested withone-endrlown on the bed plate 2 upon one Qr-theother of theshim plates 20b, 22! iand -betweenthe gauge'contact edges H), H .oflwthe anvil 6 and follower slide 8.- The slide 3 is: them-moved forwardly to grip the cylindrical comparator'between the contact edges H),- i i, and the spring stop 3-l then adjusted so as to compress zthersprin 23; whichcthen yieldingly presses the slide 3 ontinuously forwardzagainst the side wall .of the cylindrical comparator. The dial indicator 38 is next adjusted, by means of the adjusting thumb nut 56, to bring the magnet 48 on the indicator actuating spindle 40 into abutting engagement with the rear edge 49 of the slide 8 and with the spindle 40 depressed a slight distance from its outermost limiting position to bring the dial needle 42 into a definitely predetermined position on the face of the dial M (usually zero scale reading) and further to position the spindle :10 so as to be free to move both forwardly and rearwardly to a limited extent to thereby follow the movement of the follower slide 8 in response to any possible variations in the diameter of. the test specimen 12 which is to be subsequently gauged. With the gauge thus adjusted for gauging measurements, the test specimen I 2 is then substituted for the cylindrical comparator or master plug and rotated between the contact edges I0, II, whereupon its outside diameter in its various rotational positions will be indicated by the pointer needle 42 of the dial indicator and at the same time an indication provided of its circular trueness.

Gauging of the inside diameter of tubular articles or test specimens is accomplished in a similar manner, except that the open end of the article is placed over the upstanding pins 22 on the anvil plate 6 and slide 8 and the spring stop 3| is adjusted so as to compress the rearmost spring 24 to cause it to continuously urge the slide 8 rearwardly and thus maintain the pins 22 in continuous contact with the inside wall of the test specimen. Where the gauging device is to be used to gauge an article or test specimen which is of a magnetic material in. itself, instead of non-magnetic articles such as the brass electric lamp base shells H, the reciprocating slide 8 may in such case be dispensed with and the magnet-carrying indicator spindle d6 itself employed as the movable contact of the gauge to directly engage the test specimen.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A gauge for measuring the circular trueness of cylindrical articles comprising a frame, a stationary gauge contact on said frame, a dial indicator mounted on said frame and havin a projecting reciprocable actuating spindle floating between inner and outer limiting positions, said dial indicator being mounted on said frame with its said spindle reciprocable toward and away from the said stationary gauge contact, and movable gauge means in opposed relation to said stationary gauge contact to receive therebetween an article to be gauged, said movable gauge means comprising a permanent magnet mounted on and secured to said spindle so as to be unitary therewith.

2. A gauge for measuring the circular trueness of cylindrical articles comprising a frame, a stationary gauge contact on said frame, a movable gauge contact formed at least in part of magnetic material and slidably mounted on said frame in opposed relation to said stationary contact for movement toward and away therefrom, resilient means co-acting with said movable contact to press it against the article positioned between said contacts, a dial indicator mounted on said frame and having a projecting reciprocable actuating spindle floating between inner and outer limiting positions and engageable at its outer end with a magnetic portion of said movable contact for reciprocating movement thereby, and a permanent magnet mounted on and secured to the outer end of said spindle so as to be unitary therewith for holding the said spindle end continuously against s 6 the movable contact throu'gh the' magnetic force of attraction therebetween. f

3. A gauge for measuring the circulartrueness of cylindrical articles comprising a frame having a straight edge providing a stationary gauge contact, a follower slide formed at least in part of magnetic material and reciprocable on said frame toward and away from the said straight'edge contact, said slide having a straight edge opposed to extending parallel to said stationary straight edge contact, a compression coil spring co-acting with said slide to urge it towardthe said stationary straight edge'contact, a'dial indicator mounted on said frame and having a projecting reciprocable I actuating spindle floating between inner and outer-limiting positions and engageable at its outer end with a magnetic portion of said slide for reciprocating movement thereby, and a permanent magnet mounted on and secured to the outer end of said spindle so as to be unitary therewith for holding the said spindle end continuously against the said slide through the magnetic force of attraction therebetween.

4. A gauge for measuring the outside and inside diameter of tubular cylindrical articles comprising a frame having a straight edge providing a stationary gauge contact, a follower slide formed at least in part of magnetic material and reciprocable on said frame toward and away from the said straight edge contact, said slide having a straight edge opposed to and extending parallel to said stationary straight edge contact, a pair of upstanding pins respectively on said frame and said slide and located adjacent the said straight edges thereon, a pair of compression coil springs selectively co-operative with said slide to respectively urge it toward and away from said stationary straight edge contact, a dial indicator mounted on said frame and having a projecting reciprocable actuating spindle floating between inner and outer limiting positions and engageable at its outer end with a magnetic portion of said slide for reciprocating movement thereby, and a permanent magnet mounted on and secured to the outer end of said spindle so as to be unitary therewith for holding the said spindle and continuously against the said slide through the magnetic force of attraction therebetween.

5. A gauge for measuring the circular trueness of cylindrical articles comprising an elongated frame, a stationary gauge contact on said frame, a movable gauge contact formed at least in part of magnetic material and slidably mounted on said frame in opposed relation to said stationary contact for reciprocating movement longitudinally of the frame toward and away from said stationary contact, a coil spring co-acting with said movable contact to press it against the article positioned between said contacts, spring energizing means adjustable on said frame to energize said spring means, a dial indicator mounted on said frame and having a projecting reciprocable actuating spindle floating between inner and outer limiting positions and engageable at its outer end with a magnetic portion of said movable contact for reciprocating movement thereby, an adjustment rod on said frame connected to said dial indicator for adjusting it longitudinally of the frame to engage the said spindle end with said movable contact, said rod extending through and supporting said coil spring, and a permanent magnet mounted on and secured to the outer end of said spindle so as to be unitary therewith for continuously holding said spindle end in engage- -zmant wiishs =saicismoxiabior cqntact, through the magnetic force of attxamflonfltherebetween.

.6 -A,dia. 1-indioa.tor comprising iii-housin ,v a dial mounfiedomsaidhousing,and provided withscale markings units-face, apointer needle pivotally mounted. on said housing toswingacross: the face ofisaididial, a spindle reoiprocably mounted on and. projecting, from said housing andoperatively connected.- to-said pointer ton-swing, it in response to-reciprocating movement;v of the spindle, said spindle floatin between inner and outer limitin positions, and aipermanent magnet mounted on eandseoured to the outer end oi said spindle so as .to-be unitary therewith.

-:LEO.C .-KRAUSE.

; UNITEDWSTATES PATENTS ;-Name Date "Stowe NOV. 7,1905

Number Number 1,210,557 1,485,355 1,634,156. 5 1,779,477 1,937,936 2,093,066 2,190,961 2197,1963

15 Number 18 Name spate Sianherry v.--, o an;.,2, 1971' Bradbu1cy Mar, 4, 1924 McCo m June28,.1 92'7 Langston 001;.28, 1930 Aldeborgh et a1 Dec. 5, 1933 vAmos Sept. 14,1937 .Webber Feb. 20, 1940 Street Apr. 16, 19,40 Hecker Oct-14, 1941 Schwartz Mar. 3,1942 Eolk e1", a1 ,Dec..10,:L946

I FOREIGN PATENTS Coun y ate Germany Oct. 3,1929 

